A fresh round of intense diplomatic efforts are under way in Egypt to broker a peaceful end to the crisis sparked by the military's overthrow of president Mohamed Morsi.
The European Union's Middle East envoy Bernardino Leon and US Deputy Secretary of State William Burns extended their stay in Cairo to hold talks with Morsi supporters and members of the army-backed interim
leadership that replaced him.
Follow our ongoing coverage of the political crisis in Egypt
Leon met Prime Minister Hazem el-Beblawi on Monday, a day after talks with Muslim Brotherhood deputy leader, Khairat el-Shater, in prison.
Meanwhile, in a renewed push to find a solution to the crisis, US senators John McCain and Lindsay Graham were expected to begin a fresh round of shuttle diplomacy in Cairo on Tuesday.
Marie Harf, a spokeswoman for the State Department in Washington, said that Burns and Leon had visited Shater on Sunday, accompanied by the foreign ministers of Qatar and the United Arab Emirates.
Harf said the visit was intended to "prevent further violence, calm tensions and facilitate an inclusive dialogue among Egyptians that can help the transition to a democratically elected civilian government".
Morsi's deputy refused to discuss the situation with the envoys, saying that the Brotherhood's position on defending Morsi's legitimacy was "unchanged", according to Muslim Brotherhood spokesman Gehad el-Haddad.
Haddad said the envoys "still carry the position that we should swallow the reality and accept that the military coup has happened and try to recover with minimum damage".
"We refuse to do so," Haddad said.
There was no agreement on how to start talks, he added.
Harf said that "as of now", Burns had no plans to meet Morsi.
Recently, EU foreign policy chief Catherine Ashton, Arab diplomats, an African delegation and German Foreign Minister Guido Westerwelle have all travelled to Cairo in a bid to defuse the crisis.
Army chief General Abdel Fattah El Sisi also held talks with Islamist political leaders, including Salafist clerics Sheikh Mohammed Hassan and Mohammed Abdel Salam, who just days before had addressed pro-Morsi supporters at a rally.
But Yasser Ali, a spokesman for the pro-Morsi demonstrators, said the clerics had met Sisi "without having been mandated".
Sisi, who also met Burns during the envoy's visit, has urged Washington to use its "leverage" with the Muslim Brotherhood to bring about an end to the protests.
He insisted that the police, not the military, would be charged with dispersing the demonstrations.
Morsi supporters continue to stage sit-in protests that have paralysed parts of the capital and further polarised an already deeply divided country.
Authorities have promised demonstrators a safe exit and said an end to their protests would allow the Muslim Brotherhood to return to political life.
But backers of the ousted leader have steadfastly refused to bow to official pressure and demand for Morsi's release and reinstatement.
More than 250 people have been killed in deadly political violence since Morsi was toppled on July 3.